MEASUREMENT OF SALIVARY INSULIN-LIKE GROWTH-FACTOR-I IN ACROMEGALY - COMPARISON WITH SERUM INSULIN-LIKE GROWTH-FACTOR-I AND GROWTH-HORMONE CONCENTRATIONS

The aim of this study was to establish the concentration of insulin-li ke growth factor-I (IGF-I) in saliva of acromegalic patients, and to c ompare it with the basal levels of serum IGF-I and growth hormone. IGF -I was determined in extracted serum or neat saliva by a disequilibriu m RIA using antibodies and iodinated ligand from Amersham and WHO 87/5 18 as standard. The detection limit of the assay was 0.5 mu g/l, and t he intra- and interassay coefficients of variations were 7.9% and 15% respectively. Our study included 13 healthy adult individuals and 17 a cromegalics. Compared with healthy adult subjects, acromegalics had si gnificantly higher salivary IGF-I concentrations (mean +/- SEM 5.4 +/- 2.64 vs. 10.5 +/- 5.69 mu g/l; p < 0.01), as well as serum IGF-I (176 +/- 42.9 vs. 520 +/- 98.8 mu g/l; p < 0.0001) and somatotropin levels (1.2 +/- 1.02 vs. 15.4 +/- 9.89 mu g/l; p < 0.0001). However, 47.1% p atients (8 out of 17) with active acromegaly had salivary IGF-I concen trations within the normal range. Serum IGF-I and somatotropin concent rations were found to follow more closely the disease activity after a denomectomy, compared with the concentrations of salivary IGF-I. These results suggest that the IGF-I levels in serum and saliva are somatot ropin-dependent. According to our results, measurement of IGF-I in sal iva cannot be considered as an additional measure for evaluation of th e disease activity in acromegaly, being less reliable than the determi nation of IGF-I and somatotropin in serum.